NIMCET 2023 — Mathematics PYQ
NIMCET | Mathematics | 2023If ∏i=1ntan(αi)=1 ∀ αi∈[0,2π] Where i=1,2,3,…,n. Then, maximum value of ∏i=1nsinαi
Choose the correct answer:
- A.
2n1
- B.
2n/21
2n/21
Explanation
<br>sinα1sinα2sinα3⋯sinαn<br>=<br>cosα1cosα2⋯cosαn<br>
Multiplying both sides by
<br>sinα1sinα2sinα3⋯sinαn,<br>
we get
<br>sin2α1sin2α2sin2α3⋯sin2αn<br>=<br>(sinα1cosα1)<br>(sinα2cosα2)<br>⋯<br>(sinαncosαn)<br>
Using the identity
<br>sinθcosθ=21sin(2θ),<br>
we obtain
<br>sin2α1sin2α2sin2α3⋯sin2αn<br>=<br>2n1<br>sin(2α1)sin(2α2)⋯sin(2αn)<br>
Since the maximum value of sinθ is 1,
<br>sin2α1sin2α2⋯sin2αn<br>≤2n1<br>
Taking square root:
<br>i=1∏nsinαi<br>≤2n/21<br>
Hence,
<br><br>Maximum value of <br>i=1∏nsinαi<br>=<br>2n/21<br><br>
Explanation
<br>sinα1sinα2sinα3⋯sinαn<br>=<br>cosα1cosα2⋯cosαn<br>
Multiplying both sides by
<br>sinα1sinα2sinα3⋯sinαn,<br>
we get
<br>sin2α1sin2α2sin2α3⋯sin2αn<br>=<br>(sinα1cosα1)<br>(sinα2cosα2)<br>⋯<br>(sinαncosαn)<br>
Using the identity
<br>sinθcosθ=21sin(2θ),<br>
we obtain
<br>sin2α1sin2α2sin2α3⋯sin2αn<br>=<br>2n1<br>sin(2α1)sin(2α2)⋯sin(2αn)<br>
Since the maximum value of sinθ is 1,
<br>sin2α1sin2α2⋯sin2αn<br>≤2n1<br>
Taking square root:
<br>i=1∏nsinαi<br>≤2n/21<br>
Hence,
<br><br>Maximum value of <br>i=1∏nsinαi<br>=<br>2n/21<br><br>

